[dart2js] Added a powerset flag for new experiment

This experiment will use a powerset abstract value domain in the inferrer


Change-Id: I216ff9c24d1e7292688426ae7bcb52b15aa2714e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153720
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Christian Altamirano <coam@google.com>

pkg/compiler/lib/src/commandline_options.dart

@@ -28,6 +28,8 @@ class Flags {
   static const String experimentalAllocationsPath =
       '--experimental-allocations-path';
 
+  static const String experimentalPowersets = '--experimental-powersets';
+
   // Temporary experiment for code generation of locals for frequently used
   // 'this' and constants.
   static const String experimentLocalNames = '--experiment-code-1';

pkg/compiler/lib/src/compiler.dart

@@ -135,9 +135,11 @@ abstract class Compiler {
     options.deriveOptions();
     options.validate();
 
-    abstractValueStrategy = options.useTrivialAbstractValueDomain
-        ? const TrivialAbstractValueStrategy()
-        : const TypeMaskStrategy();
+    abstractValueStrategy = options.experimentalPowersets
+        ? throw UnimplementedError('Powerset abstract value domain')
+        : options.useTrivialAbstractValueDomain
+            ? const TrivialAbstractValueStrategy()
+            : const TypeMaskStrategy();
     CompilerTask kernelFrontEndTask;
     selfTask = new GenericTask('self', measurer);
     _outputProvider = new _CompilerOutput(this, outputProvider);

pkg/compiler/lib/src/dart2js.dart

@@ -445,6 +445,7 @@ Future<api.CompilationResult> compile(List<String> argv,
     new OptionHandler(Flags.disableProgramSplit, passThrough),
     new OptionHandler(Flags.disableTypeInference, passThrough),
     new OptionHandler(Flags.useTrivialAbstractValueDomain, passThrough),
+    new OptionHandler(Flags.experimentalPowersets, passThrough),
     new OptionHandler(Flags.disableRtiOptimization, passThrough),
     new OptionHandler(Flags.terse, passThrough),
     new OptionHandler('--deferred-map=.+', passThrough),

pkg/compiler/lib/src/options.dart

@@ -193,6 +193,9 @@ class CompilerOptions implements DiagnosticOptions {
   /// Whether to use the trivial abstract value domain.
   bool useTrivialAbstractValueDomain = false;
 
+  /// Whether to use the powerset abstract value domain (experimental).
+  bool experimentalPowersets = false;
+
   /// Whether to disable optimization for need runtime type information.
   bool disableRtiOptimization = false;
 
@@ -428,6 +431,7 @@ class CompilerOptions implements DiagnosticOptions {
       ..disableTypeInference = _hasOption(options, Flags.disableTypeInference)
       ..useTrivialAbstractValueDomain =
           _hasOption(options, Flags.useTrivialAbstractValueDomain)
+      ..experimentalPowersets = _hasOption(options, Flags.experimentalPowersets)
       ..disableRtiOptimization =
           _hasOption(options, Flags.disableRtiOptimization)
       ..dumpInfo = _hasOption(options, Flags.dumpInfo)